Several eucalypt species are known for their capacity to massively regenerate through seeds in recently burned areas, becoming an ecological problem in regions where the species is not native. Here we study the demography and the development of highly dense Eucalyptus globulus wildling populations established one year after a fire and test two methods to control these populations. We monitored five mixed E. globulus stands across one year, in Central Portugal. We established a set of plots in each stand, with three treatments: mechanical cutting, herbicide spraying and no disturbance (control plots). Herbicide was applied in four concentrations. We tagged randomly selected plants in the control plots to monitor their growth. The initial mean wildling density was 322,000 plants ha⁻¹, the highest ever recorded in the introduced range. Wildling density was significantly dependent on the density of surrounding adult E. globulus trees. Wildling density in control plots decreased 30% in one year, although showing positive variations over time because of new recruitment. Despite seasonal growth differences, wildlings showed a high growth rate throughout the year, reaching 15.6 cm month⁻¹ in the summer. The growth rate of tagged wildings was positively affected by solar radiation and negatively affected by evapotranspiration and maximum temperature. Mechanical cutting reduced wildling density by 97% while herbicide treatment reduced density between 80% (for the lowest concentration) and 99% (for the highest concentration). Herbicide-treated plants were more likely to resprout than cut plants. Regardless of the control method adopted (cutting or herbicide), management strategies should include the follow-up of the treated areas, to detect the establishment of new recruits and resprouting.

Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga) and two white (Arinto and Chardonnay), and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary), to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis) under normal vineyard management (including pesticide application regimes). A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean = 0.6 %; max = 7.5 %), with insect pests showing a preference for the castes Baga (red) and Chardonnay (white), while bird pests avoided the caste Arinto (white). Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes, such as organic farming, can increase the potential of native biodiversity to protect against grape losses from pests under lower regimes of chemical spraying.

Non-native trees disrupt ecological processes vital to native plant communities. We studied how forests dominated by Acacia dealbata and Eucalyptus globulus affect the role of birds as dual pollinators and seed dispersers in a region heavily impacted by these two non-native species. We compared bird–plant interactions in the native and in the two non-native forest types. We constructed a multilayer regional network for each forest type and evaluated differences in network dissimilarity between networks. We also calculated the bird’s importance in connecting processes and variables associated with module diversity. To determine how the networks react to changes in species richness, we did a simulation of species richness gradient and link percentage for each forest type. The number of birds acting both as pollinators and seed dispersers was higher in native than in non-native forests. However, birds in non-native forests still play a crucial role in maintaining the ecological services provided to native plant communities. However, the eucalyptus network exhibited a concerning simplification, forcing bird species to fully exploit the few remaining resources, leaving little room for structural adjustments and limiting the ecosystem’s ability to withstand further species loss. These findings highlight how non-native trees may trigger cascading effects across trophic levels.